New research suggests that your motivation for eating that second slice of pizza could influence how well you respond to blockbuster GLP-1s like Ozempic and Wegovy.

The study sheds new light on why some people lose up to 20% of their body weight on these drugs -- while others barely budge the scale.

That's no small matter: nearly three-quarters of US adults are considered overweight or obese, putting them at higher risk for a host of chronic health problems.

In recent years, roughly 12% of Americans have turned to GLP-1s for weight loss -- and their popularity shows no signs of slowing.

"Pre-treatment assessment of eating behavior patterns may help predict who will benefit most," Professor Daisuke Yabe of Kyoto University, the study's senior author, said in a statement.

In the study, Yabe and his colleagues followed 92 people in Japan with type 2 diabetes who were newly prescribed GLP-1s.

Over the course of a year, the researchers tracked their weight, body composition, diet, blood sugar, cholesterol -- and, importantly, their eating behaviors.

The team focused on three types of eating linked to weight gain:

Across the board, most participants lost weight and body fat and saw improvements in cholesterol. Blood glucose levels improved too, though less dramatically.

When researchers dug deeper into the data, they found key differences in who benefited most from the drugs.

By three months, many participants reported eating less in response to both emotional triggers and external cues.

However, by the end of the year, emotional eating had returned to earlier levels, while external eating kept steadily declining.

In the end, external eaters -- those influenced by sights and smells -- lost the most weight and saw better blood glucose improvements compared to those who struggled with emotional or overly restricted eating.

"One possible explanation is that emotional eating is more strongly influenced by psychological factors, which may not be directly addressed by GLP-1 receptor agonist therapy," Dr Takehiro Kato of Gifu University, second author of the article, said in a statement.

GLP-1s like Ozempic and Wegovy work by mimicking a natural hormone that controls blood sugar, slows digestion, boosts feelings of fullness and dampens the brain's response to food cues -- all helping to curb appetite.

But the study suggests these mechanisms don't work as well for people whose overeating is tied to anxiety, depression or emotional distress.

"GLP-1 receptor agonists are effective for individuals who experience weight gain or elevated blood glucose levels due to overeating triggered by external stimuli," Yabe said. "However, their effectiveness is less expected in cases where emotional eating is the primary cause."

Outside experts say that doesn't mean the drugs won't work for emotional eaters -- just that they may need more than a miracle shot to see real results.

"It's not just about overeating. We need to address underlying issues first," Dr. Mir Ali, medical director of MemorialCare Surgical Weight Loss Center who wasn't involved in the study, told Healthline.

This group of people is less likely to lose weight on Ozempic,...